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{
"language": "Solidity",
"sources": {
"workspace/CSHOPPostsNFTs.sol": {
"content": "// SPDX-License-Identifier: MIT\r\npragma solidity ^0.8.0;\r\n\r\nimport \"./ERC721URIStorage.sol\";\r\nimport \"./utils/Counters.sol\";\r\n\r\ncontract CSHOPPostsNFTs is ERC721URIStorage {\r\n using Counters for Counters.Counter;\r\n Counters.Counter private _tokenIds;\r\n\r\n constructor() ERC721(\"CSHOPPostsNFTs\", \"P_CSHOP\") {\r\n }\r\n\r\n function mintPost(address _address, string memory tokenURI)\r\n public\r\n returns (uint256)\r\n {\r\n uint256 newItemId = _tokenIds.current();\r\n _mint(_address, newItemId);\r\n _setTokenURI(newItemId, tokenURI);\r\n\r\n _tokenIds.increment();\r\n return newItemId;\r\n }\r\n}"
},
"workspace/utils/Counters.sol": {
"content": "// SPDX-License-Identifier: MIT\r\n// OpenZeppelin Contracts v4.4.1 (utils/Counters.sol)\r\n\r\npragma solidity ^0.8.0;\r\n\r\n/**\r\n * @title Counters\r\n * @author Matt Condon (@shrugs)\r\n * @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number\r\n * of elements in a mapping, issuing ERC721 ids, or counting request ids.\r\n *\r\n * Include with `using Counters for Counters.Counter;`\r\n */\r\nlibrary Counters {\r\n struct Counter {\r\n // This variable should never be directly accessed by users of the library: interactions must be restricted to\r\n // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add\r\n // this feature: see https://github.com/ethereum/solidity/issues/4637\r\n uint256 _value; // default: 0\r\n }\r\n\r\n function current(Counter storage counter) internal view returns (uint256) {\r\n return counter._value;\r\n }\r\n\r\n function increment(Counter storage counter) internal {\r\n unchecked {\r\n counter._value += 1;\r\n }\r\n }\r\n\r\n function decrement(Counter storage counter) internal {\r\n uint256 value = counter._value;\r\n require(value > 0, \"Counter: decrement overflow\");\r\n unchecked {\r\n counter._value = value - 1;\r\n }\r\n }\r\n\r\n function reset(Counter storage counter) internal {\r\n counter._value = 0;\r\n }\r\n}"
},
"workspace/ERC721URIStorage.sol": {
"content": "// SPDX-License-Identifier: MIT\r\n// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/extensions/ERC721URIStorage.sol)\r\n\r\npragma solidity ^0.8.0;\r\n\r\nimport \"./ERC721.sol\";\r\n\r\n/**\r\n * @dev ERC721 token with storage based token URI management.\r\n */\r\nabstract contract ERC721URIStorage is ERC721 {\r\n using Strings for uint256;\r\n\r\n // Optional mapping for token URIs\r\n mapping(uint256 => string) private _tokenURIs;\r\n\r\n /**\r\n * @dev See {IERC721Metadata-tokenURI}.\r\n */\r\n function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {\r\n _requireMinted(tokenId);\r\n\r\n string memory _tokenURI = _tokenURIs[tokenId];\r\n string memory base = _baseURI();\r\n\r\n // If there is no base URI, return the token URI.\r\n if (bytes(base).length == 0) {\r\n return _tokenURI;\r\n }\r\n // If both are set, concatenate the baseURI and tokenURI (via abi.encodePacked).\r\n if (bytes(_tokenURI).length > 0) {\r\n return string(abi.encodePacked(base, _tokenURI));\r\n }\r\n\r\n return super.tokenURI(tokenId);\r\n }\r\n\r\n /**\r\n * @dev Sets `_tokenURI` as the tokenURI of `tokenId`.\r\n *\r\n * Requirements:\r\n *\r\n * - `tokenId` must exist.\r\n */\r\n function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {\r\n require(_exists(tokenId), \"ERC721URIStorage: URI set of nonexistent token\");\r\n _tokenURIs[tokenId] = _tokenURI;\r\n }\r\n\r\n /**\r\n * @dev See {ERC721-_burn}. This override additionally checks to see if a\r\n * token-specific URI was set for the token, and if so, it deletes the token URI from\r\n * the storage mapping.\r\n */\r\n function _burn(uint256 tokenId) internal virtual override {\r\n super._burn(tokenId);\r\n\r\n if (bytes(_tokenURIs[tokenId]).length != 0) {\r\n delete _tokenURIs[tokenId];\r\n }\r\n }\r\n}"
},
"workspace/ERC721.sol": {
"content": "// SPDX-License-Identifier: MIT\r\n// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC721/ERC721.sol)\r\n\r\npragma solidity ^0.8.0;\r\n\r\nimport \"./IERC721.sol\";\r\nimport \"./IERC721Receiver.sol\";\r\nimport \"./extensions/IERC721Metadata.sol\";\r\nimport \"./utils/Address.sol\";\r\nimport \"./utils/Context.sol\";\r\nimport \"./utils/Strings.sol\";\r\nimport \"./utils/introspection/ERC165.sol\";\r\n\r\n/**\r\n * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including\r\n * the Metadata extension, but not including the Enumerable extension, which is available separately as\r\n * {ERC721Enumerable}.\r\n */\r\ncontract ERC721 is Context, ERC165, IERC721, IERC721Metadata {\r\n using Address for address;\r\n using Strings for uint256;\r\n\r\n // Token name\r\n string private _name;\r\n\r\n // Token symbol\r\n string private _symbol;\r\n\r\n // Mapping from token ID to owner address\r\n mapping(uint256 => address) private _owners;\r\n\r\n // Mapping owner address to token count\r\n mapping(address => uint256) private _balances;\r\n\r\n // Mapping from token ID to approved address\r\n mapping(uint256 => address) private _tokenApprovals;\r\n\r\n // Mapping from owner to operator approvals\r\n mapping(address => mapping(address => bool)) private _operatorApprovals;\r\n\r\n /**\r\n * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.\r\n */\r\n constructor(string memory name_, string memory symbol_) {\r\n _name = name_;\r\n _symbol = symbol_;\r\n }\r\n\r\n /**\r\n * @dev See {IERC165-supportsInterface}.\r\n */\r\n function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {\r\n return\r\n interfaceId == type(IERC721).interfaceId ||\r\n interfaceId == type(IERC721Metadata).interfaceId ||\r\n super.supportsInterface(interfaceId);\r\n }\r\n\r\n /**\r\n * @dev See {IERC721-balanceOf}.\r\n */\r\n function balanceOf(address owner) public view virtual override returns (uint256) {\r\n require(owner != address(0), \"ERC721: address zero is not a valid owner\");\r\n return _balances[owner];\r\n }\r\n\r\n /**\r\n * @dev See {IERC721-ownerOf}.\r\n */\r\n function ownerOf(uint256 tokenId) public view virtual override returns (address) {\r\n address owner = _ownerOf(tokenId);\r\n require(owner != address(0), \"ERC721: invalid token ID\");\r\n return owner;\r\n }\r\n\r\n /**\r\n * @dev See {IERC721Metadata-name}.\r\n */\r\n function name() public view virtual override returns (string memory) {\r\n return _name;\r\n }\r\n\r\n /**\r\n * @dev See {IERC721Metadata-symbol}.\r\n */\r\n function symbol() public view virtual override returns (string memory) {\r\n return _symbol;\r\n }\r\n\r\n /**\r\n * @dev See {IERC721Metadata-tokenURI}.\r\n */\r\n function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {\r\n _requireMinted(tokenId);\r\n\r\n string memory baseURI = _baseURI();\r\n return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : \"\";\r\n }\r\n\r\n /**\r\n * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each\r\n * token will be the concatenation of the `baseURI` and the `tokenId`. Empty\r\n * by default, can be overridden in child contracts.\r\n */\r\n function _baseURI() internal view virtual returns (string memory) {\r\n return \"\";\r\n }\r\n\r\n /**\r\n * @dev See {IERC721-approve}.\r\n */\r\n function approve(address to, uint256 tokenId) public virtual override {\r\n address owner = ERC721.ownerOf(tokenId);\r\n require(to != owner, \"ERC721: approval to current owner\");\r\n\r\n require(\r\n _msgSender() == owner || isApprovedForAll(owner, _msgSender()),\r\n \"ERC721: approve caller is not token owner or approved for all\"\r\n );\r\n\r\n _approve(to, tokenId);\r\n }\r\n\r\n /**\r\n * @dev See {IERC721-getApproved}.\r\n */\r\n function getApproved(uint256 tokenId) public view virtual override returns (address) {\r\n _requireMinted(tokenId);\r\n\r\n return _tokenApprovals[tokenId];\r\n }\r\n\r\n /**\r\n * @dev See {IERC721-setApprovalForAll}.\r\n */\r\n function setApprovalForAll(address operator, bool approved) public virtual override {\r\n _setApprovalForAll(_msgSender(), operator, approved);\r\n }\r\n\r\n /**\r\n * @dev See {IERC721-isApprovedForAll}.\r\n */\r\n function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {\r\n return _operatorApprovals[owner][operator];\r\n }\r\n\r\n /**\r\n * @dev See {IERC721-transferFrom}.\r\n */\r\n function transferFrom(\r\n address from,\r\n address to,\r\n uint256 tokenId\r\n ) public virtual override {\r\n //solhint-disable-next-line max-line-length\r\n require(_isApprovedOrOwner(_msgSender(), tokenId), \"ERC721: caller is not token owner or approved\");\r\n\r\n _transfer(from, to, tokenId);\r\n }\r\n\r\n /**\r\n * @dev See {IERC721-safeTransferFrom}.\r\n */\r\n function safeTransferFrom(\r\n address from,\r\n address to,\r\n uint256 tokenId\r\n ) public virtual override {\r\n safeTransferFrom(from, to, tokenId, \"\");\r\n }\r\n\r\n /**\r\n * @dev See {IERC721-safeTransferFrom}.\r\n */\r\n function safeTransferFrom(\r\n address from,\r\n address to,\r\n uint256 tokenId,\r\n bytes memory data\r\n ) public virtual override {\r\n require(_isApprovedOrOwner(_msgSender(), tokenId), \"ERC721: caller is not token owner or approved\");\r\n _safeTransfer(from, to, tokenId, data);\r\n }\r\n\r\n /**\r\n * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients\r\n * are aware of the ERC721 protocol to prevent tokens from being forever locked.\r\n *\r\n * `data` is additional data, it has no specified format and it is sent in call to `to`.\r\n *\r\n * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.\r\n * implement alternative mechanisms to perform token transfer, such as signature-based.\r\n *\r\n * Requirements:\r\n *\r\n * - `from` cannot be the zero address.\r\n * - `to` cannot be the zero address.\r\n * - `tokenId` token must exist and be owned by `from`.\r\n * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\r\n *\r\n * Emits a {Transfer} event.\r\n */\r\n function _safeTransfer(\r\n address from,\r\n address to,\r\n uint256 tokenId,\r\n bytes memory data\r\n ) internal virtual {\r\n _transfer(from, to, tokenId);\r\n require(_checkOnERC721Received(from, to, tokenId, data), \"ERC721: transfer to non ERC721Receiver implementer\");\r\n }\r\n\r\n /**\r\n * @dev Returns the owner of the `tokenId`. Does NOT revert if token doesn't exist\r\n */\r\n function _ownerOf(uint256 tokenId) internal view virtual returns (address) {\r\n return _owners[tokenId];\r\n }\r\n\r\n /**\r\n * @dev Returns whether `tokenId` exists.\r\n *\r\n * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.\r\n *\r\n * Tokens start existing when they are minted (`_mint`),\r\n * and stop existing when they are burned (`_burn`).\r\n */\r\n function _exists(uint256 tokenId) internal view virtual returns (bool) {\r\n return _ownerOf(tokenId) != address(0);\r\n }\r\n\r\n /**\r\n * @dev Returns whether `spender` is allowed to manage `tokenId`.\r\n *\r\n * Requirements:\r\n *\r\n * - `tokenId` must exist.\r\n */\r\n function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {\r\n address owner = ERC721.ownerOf(tokenId);\r\n return (spender == owner || isApprovedForAll(owner, spender) || getApproved(tokenId) == spender);\r\n }\r\n\r\n /**\r\n * @dev Safely mints `tokenId` and transfers it to `to`.\r\n *\r\n * Requirements:\r\n *\r\n * - `tokenId` must not exist.\r\n * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\r\n *\r\n * Emits a {Transfer} event.\r\n */\r\n function _safeMint(address to, uint256 tokenId) internal virtual {\r\n _safeMint(to, tokenId, \"\");\r\n }\r\n\r\n /**\r\n * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is\r\n * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.\r\n */\r\n function _safeMint(\r\n address to,\r\n uint256 tokenId,\r\n bytes memory data\r\n ) internal virtual {\r\n _mint(to, tokenId);\r\n require(\r\n _checkOnERC721Received(address(0), to, tokenId, data),\r\n \"ERC721: transfer to non ERC721Receiver implementer\"\r\n );\r\n }\r\n\r\n /**\r\n * @dev Mints `tokenId` and transfers it to `to`.\r\n *\r\n * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible\r\n *\r\n * Requirements:\r\n *\r\n * - `tokenId` must not exist.\r\n * - `to` cannot be the zero address.\r\n *\r\n * Emits a {Transfer} event.\r\n */\r\n function _mint(address to, uint256 tokenId) internal virtual {\r\n require(to != address(0), \"ERC721: mint to the zero address\");\r\n require(!_exists(tokenId), \"ERC721: token already minted\");\r\n\r\n _beforeTokenTransfer(address(0), to, tokenId, 1);\r\n\r\n // Check that tokenId was not minted by `_beforeTokenTransfer` hook\r\n require(!_exists(tokenId), \"ERC721: token already minted\");\r\n\r\n unchecked {\r\n // Will not overflow unless all 2**256 token ids are minted to the same owner.\r\n // Given that tokens are minted one by one, it is impossible in practice that\r\n // this ever happens. Might change if we allow batch minting.\r\n // The ERC fails to describe this case.\r\n _balances[to] += 1;\r\n }\r\n\r\n _owners[tokenId] = to;\r\n\r\n emit Transfer(address(0), to, tokenId);\r\n\r\n _afterTokenTransfer(address(0), to, tokenId, 1);\r\n }\r\n\r\n /**\r\n * @dev Destroys `tokenId`.\r\n * The approval is cleared when the token is burned.\r\n * This is an internal function that does not check if the sender is authorized to operate on the token.\r\n *\r\n * Requirements:\r\n *\r\n * - `tokenId` must exist.\r\n *\r\n * Emits a {Transfer} event.\r\n */\r\n function _burn(uint256 tokenId) internal virtual {\r\n address owner = ERC721.ownerOf(tokenId);\r\n\r\n _beforeTokenTransfer(owner, address(0), tokenId, 1);\r\n\r\n // Update ownership in case tokenId was transferred by `_beforeTokenTransfer` hook\r\n owner = ERC721.ownerOf(tokenId);\r\n\r\n // Clear approvals\r\n delete _tokenApprovals[tokenId];\r\n\r\n unchecked {\r\n // Cannot overflow, as that would require more tokens to be burned/transferred\r\n // out than the owner initially received through minting and transferring in.\r\n _balances[owner] -= 1;\r\n }\r\n delete _owners[tokenId];\r\n\r\n emit Transfer(owner, address(0), tokenId);\r\n\r\n _afterTokenTransfer(owner, address(0), tokenId, 1);\r\n }\r\n\r\n /**\r\n * @dev Transfers `tokenId` from `from` to `to`.\r\n * As opposed to {transferFrom}, this imposes no restrictions on msg.sender.\r\n *\r\n * Requirements:\r\n *\r\n * - `to` cannot be the zero address.\r\n * - `tokenId` token must be owned by `from`.\r\n *\r\n * Emits a {Transfer} event.\r\n */\r\n function _transfer(\r\n address from,\r\n address to,\r\n uint256 tokenId\r\n ) internal virtual {\r\n require(ERC721.ownerOf(tokenId) == from, \"ERC721: transfer from incorrect owner\");\r\n require(to != address(0), \"ERC721: transfer to the zero address\");\r\n\r\n _beforeTokenTransfer(from, to, tokenId, 1);\r\n\r\n // Check that tokenId was not transferred by `_beforeTokenTransfer` hook\r\n require(ERC721.ownerOf(tokenId) == from, \"ERC721: transfer from incorrect owner\");\r\n\r\n // Clear approvals from the previous owner\r\n delete _tokenApprovals[tokenId];\r\n\r\n unchecked {\r\n // `_balances[from]` cannot overflow for the same reason as described in `_burn`:\r\n // `from`'s balance is the number of token held, which is at least one before the current\r\n // transfer.\r\n // `_balances[to]` could overflow in the conditions described in `_mint`. That would require\r\n // all 2**256 token ids to be minted, which in practice is impossible.\r\n _balances[from] -= 1;\r\n _balances[to] += 1;\r\n }\r\n _owners[tokenId] = to;\r\n\r\n emit Transfer(from, to, tokenId);\r\n\r\n _afterTokenTransfer(from, to, tokenId, 1);\r\n }\r\n\r\n /**\r\n * @dev Approve `to` to operate on `tokenId`\r\n *\r\n * Emits an {Approval} event.\r\n */\r\n function _approve(address to, uint256 tokenId) internal virtual {\r\n _tokenApprovals[tokenId] = to;\r\n emit Approval(ERC721.ownerOf(tokenId), to, tokenId);\r\n }\r\n\r\n /**\r\n * @dev Approve `operator` to operate on all of `owner` tokens\r\n *\r\n * Emits an {ApprovalForAll} event.\r\n */\r\n function _setApprovalForAll(\r\n address owner,\r\n address operator,\r\n bool approved\r\n ) internal virtual {\r\n require(owner != operator, \"ERC721: approve to caller\");\r\n _operatorApprovals[owner][operator] = approved;\r\n emit ApprovalForAll(owner, operator, approved);\r\n }\r\n\r\n /**\r\n * @dev Reverts if the `tokenId` has not been minted yet.\r\n */\r\n function _requireMinted(uint256 tokenId) internal view virtual {\r\n require(_exists(tokenId), \"ERC721: invalid token ID\");\r\n }\r\n\r\n /**\r\n * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.\r\n * The call is not executed if the target address is not a contract.\r\n *\r\n * @param from address representing the previous owner of the given token ID\r\n * @param to target address that will receive the tokens\r\n * @param tokenId uint256 ID of the token to be transferred\r\n * @param data bytes optional data to send along with the call\r\n * @return bool whether the call correctly returned the expected magic value\r\n */\r\n function _checkOnERC721Received(\r\n address from,\r\n address to,\r\n uint256 tokenId,\r\n bytes memory data\r\n ) private returns (bool) {\r\n if (to.isContract()) {\r\n try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, data) returns (bytes4 retval) {\r\n return retval == IERC721Receiver.onERC721Received.selector;\r\n } catch (bytes memory reason) {\r\n if (reason.length == 0) {\r\n revert(\"ERC721: transfer to non ERC721Receiver implementer\");\r\n } else {\r\n /// @solidity memory-safe-assembly\r\n assembly {\r\n revert(add(32, reason), mload(reason))\r\n }\r\n }\r\n }\r\n } else {\r\n return true;\r\n }\r\n }\r\n\r\n /**\r\n * @dev Hook that is called before any token transfer. This includes minting and burning. If {ERC721Consecutive} is\r\n * used, the hook may be called as part of a consecutive (batch) mint, as indicated by `batchSize` greater than 1.\r\n *\r\n * Calling conditions:\r\n *\r\n * - When `from` and `to` are both non-zero, ``from``'s tokens will be transferred to `to`.\r\n * - When `from` is zero, the tokens will be minted for `to`.\r\n * - When `to` is zero, ``from``'s tokens will be burned.\r\n * - `from` and `to` are never both zero.\r\n * - `batchSize` is non-zero.\r\n *\r\n * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].\r\n */\r\n function _beforeTokenTransfer(\r\n address from,\r\n address to,\r\n uint256, /* firstTokenId */\r\n uint256 batchSize\r\n ) internal virtual {\r\n if (batchSize > 1) {\r\n if (from != address(0)) {\r\n _balances[from] -= batchSize;\r\n }\r\n if (to != address(0)) {\r\n _balances[to] += batchSize;\r\n }\r\n }\r\n }\r\n\r\n /**\r\n * @dev Hook that is called after any token transfer. This includes minting and burning. If {ERC721Consecutive} is\r\n * used, the hook may be called as part of a consecutive (batch) mint, as indicated by `batchSize` greater than 1.\r\n *\r\n * Calling conditions:\r\n *\r\n * - When `from` and `to` are both non-zero, ``from``'s tokens were transferred to `to`.\r\n * - When `from` is zero, the tokens were minted for `to`.\r\n * - When `to` is zero, ``from``'s tokens were burned.\r\n * - `from` and `to` are never both zero.\r\n * - `batchSize` is non-zero.\r\n *\r\n * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].\r\n */\r\n function _afterTokenTransfer(\r\n address from,\r\n address to,\r\n uint256 firstTokenId,\r\n uint256 batchSize\r\n ) internal virtual {}\r\n}"
},
"workspace/utils/introspection/ERC165.sol": {
"content": "// SPDX-License-Identifier: MIT\r\n// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)\r\n\r\npragma solidity ^0.8.0;\r\n\r\nimport \"./IERC165.sol\";\r\n\r\n/**\r\n * @dev Implementation of the {IERC165} interface.\r\n *\r\n * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check\r\n * for the additional interface id that will be supported. For example:\r\n *\r\n * ```solidity\r\n * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {\r\n * return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);\r\n * }\r\n * ```\r\n *\r\n * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.\r\n */\r\nabstract contract ERC165 is IERC165 {\r\n /**\r\n * @dev See {IERC165-supportsInterface}.\r\n */\r\n function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {\r\n return interfaceId == type(IERC165).interfaceId;\r\n }\r\n}"
},
"workspace/utils/Strings.sol": {
"content": "// SPDX-License-Identifier: MIT\r\n// OpenZeppelin Contracts (last updated v4.8.0) (utils/Strings.sol)\r\n\r\npragma solidity ^0.8.0;\r\n\r\nimport \"./math/Math.sol\";\r\n\r\n/**\r\n * @dev String operations.\r\n */\r\nlibrary Strings {\r\n bytes16 private constant _SYMBOLS = \"0123456789abcdef\";\r\n uint8 private constant _ADDRESS_LENGTH = 20;\r\n\r\n /**\r\n * @dev Converts a `uint256` to its ASCII `string` decimal representation.\r\n */\r\n function toString(uint256 value) internal pure returns (string memory) {\r\n unchecked {\r\n uint256 length = Math.log10(value) + 1;\r\n string memory buffer = new string(length);\r\n uint256 ptr;\r\n /// @solidity memory-safe-assembly\r\n assembly {\r\n ptr := add(buffer, add(32, length))\r\n }\r\n while (true) {\r\n ptr--;\r\n /// @solidity memory-safe-assembly\r\n assembly {\r\n mstore8(ptr, byte(mod(value, 10), _SYMBOLS))\r\n }\r\n value /= 10;\r\n if (value == 0) break;\r\n }\r\n return buffer;\r\n }\r\n }\r\n\r\n /**\r\n * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.\r\n */\r\n function toHexString(uint256 value) internal pure returns (string memory) {\r\n unchecked {\r\n return toHexString(value, Math.log256(value) + 1);\r\n }\r\n }\r\n\r\n /**\r\n * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.\r\n */\r\n function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {\r\n bytes memory buffer = new bytes(2 * length + 2);\r\n buffer[0] = \"0\";\r\n buffer[1] = \"x\";\r\n for (uint256 i = 2 * length + 1; i > 1; --i) {\r\n buffer[i] = _SYMBOLS[value & 0xf];\r\n value >>= 4;\r\n }\r\n require(value == 0, \"Strings: hex length insufficient\");\r\n return string(buffer);\r\n }\r\n\r\n /**\r\n * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.\r\n */\r\n function toHexString(address addr) internal pure returns (string memory) {\r\n return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);\r\n }\r\n}"
},
"workspace/utils/Context.sol": {
"content": "// SPDX-License-Identifier: MIT\r\n// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)\r\n\r\npragma solidity >=0.4.22 <0.9.0;\r\n\r\n/**\r\n * @dev Provides information about the current execution context, including the\r\n * sender of the transaction and its data. While these are generally available\r\n * via msg.sender and msg.data, they should not be accessed in such a direct\r\n * manner, since when dealing with meta-transactions the account sending and\r\n * paying for execution may not be the actual sender (as far as an application\r\n * is concerned).\r\n *\r\n * This contract is only required for intermediate, library-like contracts.\r\n */\r\nabstract contract Context {\r\n function _msgSender() internal view virtual returns (address) {\r\n return msg.sender;\r\n }\r\n\r\n function _msgData() internal view virtual returns (bytes calldata) {\r\n return msg.data;\r\n }\r\n}"
},
"workspace/utils/Address.sol": {
"content": "// SPDX-License-Identifier: MIT\r\n// OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)\r\n\r\npragma solidity ^0.8.1;\r\n\r\n/**\r\n * @dev Collection of functions related to the address type\r\n */\r\nlibrary Address {\r\n /**\r\n * @dev Returns true if `account` is a contract.\r\n *\r\n * [IMPORTANT]\r\n * ====\r\n * It is unsafe to assume that an address for which this function returns\r\n * false is an externally-owned account (EOA) and not a contract.\r\n *\r\n * Among others, `isContract` will return false for the following\r\n * types of addresses:\r\n *\r\n * - an externally-owned account\r\n * - a contract in construction\r\n * - an address where a contract will be created\r\n * - an address where a contract lived, but was destroyed\r\n * ====\r\n *\r\n * [IMPORTANT]\r\n * ====\r\n * You shouldn't rely on `isContract` to protect against flash loan attacks!\r\n *\r\n * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets\r\n * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract\r\n * constructor.\r\n * ====\r\n */\r\n function isContract(address account) internal view returns (bool) {\r\n // This method relies on extcodesize/address.code.length, which returns 0\r\n // for contracts in construction, since the code is only stored at the end\r\n // of the constructor execution.\r\n\r\n return account.code.length > 0;\r\n }\r\n\r\n /**\r\n * @dev Replacement for Solidity's `transfer`: sends `amount` wei to\r\n * `recipient`, forwarding all available gas and reverting on errors.\r\n *\r\n * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost\r\n * of certain opcodes, possibly making contracts go over the 2300 gas limit\r\n * imposed by `transfer`, making them unable to receive funds via\r\n * `transfer`. {sendValue} removes this limitation.\r\n *\r\n * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].\r\n *\r\n * IMPORTANT: because control is transferred to `recipient`, care must be\r\n * taken to not create reentrancy vulnerabilities. Consider using\r\n * {ReentrancyGuard} or the\r\n * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].\r\n */\r\n function sendValue(address payable recipient, uint256 amount) internal {\r\n require(address(this).balance >= amount, \"Address: insufficient balance\");\r\n\r\n (bool success, ) = recipient.call{value: amount}(\"\");\r\n require(success, \"Address: unable to send value, recipient may have reverted\");\r\n }\r\n\r\n /**\r\n * @dev Performs a Solidity function call using a low level `call`. A\r\n * plain `call` is an unsafe replacement for a function call: use this\r\n * function instead.\r\n *\r\n * If `target` reverts with a revert reason, it is bubbled up by this\r\n * function (like regular Solidity function calls).\r\n *\r\n * Returns the raw returned data. To convert to the expected return value,\r\n * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].\r\n *\r\n * Requirements:\r\n *\r\n * - `target` must be a contract.\r\n * - calling `target` with `data` must not revert.\r\n *\r\n * _Available since v3.1._\r\n */\r\n function functionCall(address target, bytes memory data) internal returns (bytes memory) {\r\n return functionCallWithValue(target, data, 0, \"Address: low-level call failed\");\r\n }\r\n\r\n /**\r\n * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with\r\n * `errorMessage` as a fallback revert reason when `target` reverts.\r\n *\r\n * _Available since v3.1._\r\n */\r\n function functionCall(\r\n address target,\r\n bytes memory data,\r\n string memory errorMessage\r\n ) internal returns (bytes memory) {\r\n return functionCallWithValue(target, data, 0, errorMessage);\r\n }\r\n\r\n /**\r\n * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\r\n * but also transferring `value` wei to `target`.\r\n *\r\n * Requirements:\r\n *\r\n * - the calling contract must have an ETH balance of at least `value`.\r\n * - the called Solidity function must be `payable`.\r\n *\r\n * _Available since v3.1._\r\n */\r\n function functionCallWithValue(\r\n address target,\r\n bytes memory data,\r\n uint256 value\r\n ) internal returns (bytes memory) {\r\n return functionCallWithValue(target, data, value, \"Address: low-level call with value failed\");\r\n }\r\n\r\n /**\r\n * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but\r\n * with `errorMessage` as a fallback revert reason when `target` reverts.\r\n *\r\n * _Available since v3.1._\r\n */\r\n function functionCallWithValue(\r\n address target,\r\n bytes memory data,\r\n uint256 value,\r\n string memory errorMessage\r\n ) internal returns (bytes memory) {\r\n require(address(this).balance >= value, \"Address: insufficient balance for call\");\r\n (bool success, bytes memory returndata) = target.call{value: value}(data);\r\n return verifyCallResultFromTarget(target, success, returndata, errorMessage);\r\n }\r\n\r\n /**\r\n * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\r\n * but performing a static call.\r\n *\r\n * _Available since v3.3._\r\n */\r\n function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {\r\n return functionStaticCall(target, data, \"Address: low-level static call failed\");\r\n }\r\n\r\n /**\r\n * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],\r\n * but performing a static call.\r\n *\r\n * _Available since v3.3._\r\n */\r\n function functionStaticCall(\r\n address target,\r\n bytes memory data,\r\n string memory errorMessage\r\n ) internal view returns (bytes memory) {\r\n (bool success, bytes memory returndata) = target.staticcall(data);\r\n return verifyCallResultFromTarget(target, success, returndata, errorMessage);\r\n }\r\n\r\n /**\r\n * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\r\n * but performing a delegate call.\r\n *\r\n * _Available since v3.4._\r\n */\r\n function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {\r\n return functionDelegateCall(target, data, \"Address: low-level delegate call failed\");\r\n }\r\n\r\n /**\r\n * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],\r\n * but performing a delegate call.\r\n *\r\n * _Available since v3.4._\r\n */\r\n function functionDelegateCall(\r\n address target,\r\n bytes memory data,\r\n string memory errorMessage\r\n ) internal returns (bytes memory) {\r\n (bool success, bytes memory returndata) = target.delegatecall(data);\r\n return verifyCallResultFromTarget(target, success, returndata, errorMessage);\r\n }\r\n\r\n /**\r\n * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling\r\n * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.\r\n *\r\n * _Available since v4.8._\r\n */\r\n function verifyCallResultFromTarget(\r\n address target,\r\n bool success,\r\n bytes memory returndata,\r\n string memory errorMessage\r\n ) internal view returns (bytes memory) {\r\n if (success) {\r\n if (returndata.length == 0) {\r\n // only check isContract if the call was successful and the return data is empty\r\n // otherwise we already know that it was a contract\r\n require(isContract(target), \"Address: call to non-contract\");\r\n }\r\n return returndata;\r\n } else {\r\n _revert(returndata, errorMessage);\r\n }\r\n }\r\n\r\n /**\r\n * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the\r\n * revert reason or using the provided one.\r\n *\r\n * _Available since v4.3._\r\n */\r\n function verifyCallResult(\r\n bool success,\r\n bytes memory returndata,\r\n string memory errorMessage\r\n ) internal pure returns (bytes memory) {\r\n if (success) {\r\n return returndata;\r\n } else {\r\n _revert(returndata, errorMessage);\r\n }\r\n }\r\n\r\n function _revert(bytes memory returndata, string memory errorMessage) private pure {\r\n // Look for revert reason and bubble it up if present\r\n if (returndata.length > 0) {\r\n // The easiest way to bubble the revert reason is using memory via assembly\r\n /// @solidity memory-safe-assembly\r\n assembly {\r\n let returndata_size := mload(returndata)\r\n revert(add(32, returndata), returndata_size)\r\n }\r\n } else {\r\n revert(errorMessage);\r\n }\r\n }\r\n}"
},
"workspace/extensions/IERC721Metadata.sol": {
"content": "// SPDX-License-Identifier: MIT\r\n// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)\r\n\r\npragma solidity ^0.8.0;\r\n\r\nimport \"../IERC721.sol\";\r\n\r\n/**\r\n * @title ERC-721 Non-Fungible Token Standard, optional metadata extension\r\n * @dev See https://eips.ethereum.org/EIPS/eip-721\r\n */\r\ninterface IERC721Metadata is IERC721 {\r\n /**\r\n * @dev Returns the token collection name.\r\n */\r\n function name() external view returns (string memory);\r\n\r\n /**\r\n * @dev Returns the token collection symbol.\r\n */\r\n function symbol() external view returns (string memory);\r\n\r\n /**\r\n * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.\r\n */\r\n function tokenURI(uint256 tokenId) external view returns (string memory);\r\n}"
},
"workspace/IERC721Receiver.sol": {
"content": "// SPDX-License-Identifier: MIT\r\n// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC721/IERC721Receiver.sol)\r\n\r\npragma solidity ^0.8.0;\r\n\r\n/**\r\n * @title ERC721 token receiver interface\r\n * @dev Interface for any contract that wants to support safeTransfers\r\n * from ERC721 asset contracts.\r\n */\r\ninterface IERC721Receiver {\r\n /**\r\n * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}\r\n * by `operator` from `from`, this function is called.\r\n *\r\n * It must return its Solidity selector to confirm the token transfer.\r\n * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.\r\n *\r\n * The selector can be obtained in Solidity with `IERC721Receiver.onERC721Received.selector`.\r\n */\r\n function onERC721Received(\r\n address operator,\r\n address from,\r\n uint256 tokenId,\r\n bytes calldata data\r\n ) external returns (bytes4);\r\n}"
},
"workspace/IERC721.sol": {
"content": "// SPDX-License-Identifier: MIT\r\n// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC721/IERC721.sol)\r\n\r\npragma solidity ^0.8.0;\r\n\r\nimport \"./utils/introspection/IERC165.sol\";\r\n\r\n/**\r\n * @dev Required interface of an ERC721 compliant contract.\r\n */\r\ninterface IERC721 is IERC165 {\r\n /**\r\n * @dev Emitted when `tokenId` token is transferred from `from` to `to`.\r\n */\r\n event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);\r\n\r\n /**\r\n * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.\r\n */\r\n event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);\r\n\r\n /**\r\n * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.\r\n */\r\n event ApprovalForAll(address indexed owner, address indexed operator, bool approved);\r\n\r\n /**\r\n * @dev Returns the number of tokens in ``owner``'s account.\r\n */\r\n function balanceOf(address owner) external view returns (uint256 balance);\r\n\r\n /**\r\n * @dev Returns the owner of the `tokenId` token.\r\n *\r\n * Requirements:\r\n *\r\n * - `tokenId` must exist.\r\n */\r\n function ownerOf(uint256 tokenId) external view returns (address owner);\r\n\r\n /**\r\n * @dev Safely transfers `tokenId` token from `from` to `to`.\r\n *\r\n * Requirements:\r\n *\r\n * - `from` cannot be the zero address.\r\n * - `to` cannot be the zero address.\r\n * - `tokenId` token must exist and be owned by `from`.\r\n * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.\r\n * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\r\n *\r\n * Emits a {Transfer} event.\r\n */\r\n function safeTransferFrom(\r\n address from,\r\n address to,\r\n uint256 tokenId,\r\n bytes calldata data\r\n ) external;\r\n\r\n /**\r\n * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients\r\n * are aware of the ERC721 protocol to prevent tokens from being forever locked.\r\n *\r\n * Requirements:\r\n *\r\n * - `from` cannot be the zero address.\r\n * - `to` cannot be the zero address.\r\n * - `tokenId` token must exist and be owned by `from`.\r\n * - If the caller is not `from`, it must have been allowed to move this token by either {approve} or {setApprovalForAll}.\r\n * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\r\n *\r\n * Emits a {Transfer} event.\r\n */\r\n function safeTransferFrom(\r\n address from,\r\n address to,\r\n uint256 tokenId\r\n ) external;\r\n\r\n /**\r\n * @dev Transfers `tokenId` token from `from` to `to`.\r\n *\r\n * WARNING: Note that the caller is responsible to confirm that the recipient is capable of receiving ERC721\r\n * or else they may be permanently lost. Usage of {safeTransferFrom} prevents loss, though the caller must\r\n * understand this adds an external call which potentially creates a reentrancy vulnerability.\r\n *\r\n * Requirements:\r\n *\r\n * - `from` cannot be the zero address.\r\n * - `to` cannot be the zero address.\r\n * - `tokenId` token must be owned by `from`.\r\n * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.\r\n *\r\n * Emits a {Transfer} event.\r\n */\r\n function transferFrom(\r\n address from,\r\n address to,\r\n uint256 tokenId\r\n ) external;\r\n\r\n /**\r\n * @dev Gives permission to `to` to transfer `tokenId` token to another account.\r\n * The approval is cleared when the token is transferred.\r\n *\r\n * Only a single account can be approved at a time, so approving the zero address clears previous approvals.\r\n *\r\n * Requirements:\r\n *\r\n * - The caller must own the token or be an approved operator.\r\n * - `tokenId` must exist.\r\n *\r\n * Emits an {Approval} event.\r\n */\r\n function approve(address to, uint256 tokenId) external;\r\n\r\n /**\r\n * @dev Approve or remove `operator` as an operator for the caller.\r\n * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.\r\n *\r\n * Requirements:\r\n *\r\n * - The `operator` cannot be the caller.\r\n *\r\n * Emits an {ApprovalForAll} event.\r\n */\r\n function setApprovalForAll(address operator, bool _approved) external;\r\n\r\n /**\r\n * @dev Returns the account approved for `tokenId` token.\r\n *\r\n * Requirements:\r\n *\r\n * - `tokenId` must exist.\r\n */\r\n function getApproved(uint256 tokenId) external view returns (address operator);\r\n\r\n /**\r\n * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.\r\n *\r\n * See {setApprovalForAll}\r\n */\r\n function isApprovedForAll(address owner, address operator) external view returns (bool);\r\n}"
},
"workspace/utils/introspection/IERC165.sol": {
"content": "// SPDX-License-Identifier: MIT\r\n// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)\r\n\r\npragma solidity ^0.8.0;\r\n\r\n/**\r\n * @dev Interface of the ERC165 standard, as defined in the\r\n * https://eips.ethereum.org/EIPS/eip-165[EIP].\r\n *\r\n * Implementers can declare support of contract interfaces, which can then be\r\n * queried by others ({ERC165Checker}).\r\n *\r\n * For an implementation, see {ERC165}.\r\n */\r\ninterface IERC165 {\r\n /**\r\n * @dev Returns true if this contract implements the interface defined by\r\n * `interfaceId`. See the corresponding\r\n * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]\r\n * to learn more about how these ids are created.\r\n *\r\n * This function call must use less than 30 000 gas.\r\n */\r\n function supportsInterface(bytes4 interfaceId) external view returns (bool);\r\n}"
},
"workspace/utils/math/Math.sol": {
"content": "// SPDX-License-Identifier: MIT\r\n// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/Math.sol)\r\n\r\npragma solidity ^0.8.0;\r\n\r\n/**\r\n * @dev Standard math utilities missing in the Solidity language.\r\n */\r\nlibrary Math {\r\n enum Rounding {\r\n Down, // Toward negative infinity\r\n Up, // Toward infinity\r\n Zero // Toward zero\r\n }\r\n\r\n /**\r\n * @dev Returns the largest of two numbers.\r\n */\r\n function max(uint256 a, uint256 b) internal pure returns (uint256) {\r\n return a > b ? a : b;\r\n }\r\n\r\n /**\r\n * @dev Returns the smallest of two numbers.\r\n */\r\n function min(uint256 a, uint256 b) internal pure returns (uint256) {\r\n return a < b ? a : b;\r\n }\r\n\r\n /**\r\n * @dev Returns the average of two numbers. The result is rounded towards\r\n * zero.\r\n */\r\n function average(uint256 a, uint256 b) internal pure returns (uint256) {\r\n // (a + b) / 2 can overflow.\r\n return (a & b) + (a ^ b) / 2;\r\n }\r\n\r\n /**\r\n * @dev Returns the ceiling of the division of two numbers.\r\n *\r\n * This differs from standard division with `/` in that it rounds up instead\r\n * of rounding down.\r\n */\r\n function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {\r\n // (a + b - 1) / b can overflow on addition, so we distribute.\r\n return a == 0 ? 0 : (a - 1) / b + 1;\r\n }\r\n\r\n /**\r\n * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or denominator == 0\r\n * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv)\r\n * with further edits by Uniswap Labs also under MIT license.\r\n */\r\n function mulDiv(\r\n uint256 x,\r\n uint256 y,\r\n uint256 denominator\r\n ) internal pure returns (uint256 result) {\r\n unchecked {\r\n // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use\r\n // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256\r\n // variables such that product = prod1 * 2^256 + prod0.\r\n uint256 prod0; // Least significant 256 bits of the product\r\n uint256 prod1; // Most significant 256 bits of the product\r\n assembly {\r\n let mm := mulmod(x, y, not(0))\r\n prod0 := mul(x, y)\r\n prod1 := sub(sub(mm, prod0), lt(mm, prod0))\r\n }\r\n\r\n // Handle non-overflow cases, 256 by 256 division.\r\n if (prod1 == 0) {\r\n return prod0 / denominator;\r\n }\r\n\r\n // Make sure the result is less than 2^256. Also prevents denominator == 0.\r\n require(denominator > prod1);\r\n\r\n ///////////////////////////////////////////////\r\n // 512 by 256 division.\r\n ///////////////////////////////////////////////\r\n\r\n // Make division exact by subtracting the remainder from [prod1 prod0].\r\n uint256 remainder;\r\n assembly {\r\n // Compute remainder using mulmod.\r\n remainder := mulmod(x, y, denominator)\r\n\r\n // Subtract 256 bit number from 512 bit number.\r\n prod1 := sub(prod1, gt(remainder, prod0))\r\n prod0 := sub(prod0, remainder)\r\n }\r\n\r\n // Factor powers of two out of denominator and compute largest power of two divisor of denominator. Always >= 1.\r\n // See https://cs.stackexchange.com/q/138556/92363.\r\n\r\n // Does not overflow because the denominator cannot be zero at this stage in the function.\r\n uint256 twos = denominator & (~denominator + 1);\r\n assembly {\r\n // Divide denominator by twos.\r\n denominator := div(denominator, twos)\r\n\r\n // Divide [prod1 prod0] by twos.\r\n prod0 := div(prod0, twos)\r\n\r\n // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.\r\n twos := add(div(sub(0, twos), twos), 1)\r\n }\r\n\r\n // Shift in bits from prod1 into prod0.\r\n prod0 |= prod1 * twos;\r\n\r\n // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such\r\n // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for\r\n // four bits. That is, denominator * inv = 1 mod 2^4.\r\n uint256 inverse = (3 * denominator) ^ 2;\r\n\r\n // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also works\r\n // in modular arithmetic, doubling the correct bits in each step.\r\n inverse *= 2 - denominator * inverse; // inverse mod 2^8\r\n inverse *= 2 - denominator * inverse; // inverse mod 2^16\r\n inverse *= 2 - denominator * inverse; // inverse mod 2^32\r\n inverse *= 2 - denominator * inverse; // inverse mod 2^64\r\n inverse *= 2 - denominator * inverse; // inverse mod 2^128\r\n inverse *= 2 - denominator * inverse; // inverse mod 2^256\r\n\r\n // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.\r\n // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is\r\n // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1\r\n // is no longer required.\r\n result = prod0 * inverse;\r\n return result;\r\n }\r\n }\r\n\r\n /**\r\n * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.\r\n */\r\n function mulDiv(\r\n uint256 x,\r\n uint256 y,\r\n uint256 denominator,\r\n Rounding rounding\r\n ) internal pure returns (uint256) {\r\n uint256 result = mulDiv(x, y, denominator);\r\n if (rounding == Rounding.Up && mulmod(x, y, denominator) > 0) {\r\n result += 1;\r\n }\r\n return result;\r\n }\r\n\r\n /**\r\n * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded down.\r\n *\r\n * Inspired by Henry S. Warren, Jr.'s \"Hacker's Delight\" (Chapter 11).\r\n */\r\n function sqrt(uint256 a) internal pure returns (uint256) {\r\n if (a == 0) {\r\n return 0;\r\n }\r\n\r\n // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.\r\n //\r\n // We know that the \"msb\" (most significant bit) of our target number `a` is a power of 2 such that we have\r\n // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.\r\n //\r\n // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`\r\n // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`\r\n // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`\r\n //\r\n // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.\r\n uint256 result = 1 << (log2(a) >> 1);\r\n\r\n // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,\r\n // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at\r\n // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision\r\n // into the expected uint128 result.\r\n unchecked {\r\n result = (result + a / result) >> 1;\r\n result = (result + a / result) >> 1;\r\n result = (result + a / result) >> 1;\r\n result = (result + a / result) >> 1;\r\n result = (result + a / result) >> 1;\r\n result = (result + a / result) >> 1;\r\n result = (result + a / result) >> 1;\r\n return min(result, a / result);\r\n }\r\n }\r\n\r\n /**\r\n * @notice Calculates sqrt(a), following the selected rounding direction.\r\n */\r\n function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {\r\n unchecked {\r\n uint256 result = sqrt(a);\r\n return result + (rounding == Rounding.Up && result * result < a ? 1 : 0);\r\n }\r\n }\r\n\r\n /**\r\n * @dev Return the log in base 2, rounded down, of a positive value.\r\n * Returns 0 if given 0.\r\n */\r\n function log2(uint256 value) internal pure returns (uint256) {\r\n uint256 result = 0;\r\n unchecked {\r\n if (value >> 128 > 0) {\r\n value >>= 128;\r\n result += 128;\r\n }\r\n if (value >> 64 > 0) {\r\n value >>= 64;\r\n result += 64;\r\n }\r\n if (value >> 32 > 0) {\r\n value >>= 32;\r\n result += 32;\r\n }\r\n if (value >> 16 > 0) {\r\n value >>= 16;\r\n result += 16;\r\n }\r\n if (value >> 8 > 0) {\r\n value >>= 8;\r\n result += 8;\r\n }\r\n if (value >> 4 > 0) {\r\n value >>= 4;\r\n result += 4;\r\n }\r\n if (value >> 2 > 0) {\r\n value >>= 2;\r\n result += 2;\r\n }\r\n if (value >> 1 > 0) {\r\n result += 1;\r\n }\r\n }\r\n return result;\r\n }\r\n\r\n /**\r\n * @dev Return the log in base 2, following the selected rounding direction, of a positive value.\r\n * Returns 0 if given 0.\r\n */\r\n function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {\r\n unchecked {\r\n uint256 result = log2(value);\r\n return result + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);\r\n }\r\n }\r\n\r\n /**\r\n * @dev Return the log in base 10, rounded down, of a positive value.\r\n * Returns 0 if given 0.\r\n */\r\n function log10(uint256 value) internal pure returns (uint256) {\r\n uint256 result = 0;\r\n unchecked {\r\n if (value >= 10**64) {\r\n value /= 10**64;\r\n result += 64;\r\n }\r\n if (value >= 10**32) {\r\n value /= 10**32;\r\n result += 32;\r\n }\r\n if (value >= 10**16) {\r\n value /= 10**16;\r\n result += 16;\r\n }\r\n if (value >= 10**8) {\r\n value /= 10**8;\r\n result += 8;\r\n }\r\n if (value >= 10**4) {\r\n value /= 10**4;\r\n result += 4;\r\n }\r\n if (value >= 10**2) {\r\n value /= 10**2;\r\n result += 2;\r\n }\r\n if (value >= 10**1) {\r\n result += 1;\r\n }\r\n }\r\n return result;\r\n }\r\n\r\n /**\r\n * @dev Return the log in base 10, following the selected rounding direction, of a positive value.\r\n * Returns 0 if given 0.\r\n */\r\n function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {\r\n unchecked {\r\n uint256 result = log10(value);\r\n return result + (rounding == Rounding.Up && 10**result < value ? 1 : 0);\r\n }\r\n }\r\n\r\n /**\r\n * @dev Return the log in base 256, rounded down, of a positive value.\r\n * Returns 0 if given 0.\r\n *\r\n * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.\r\n */\r\n function log256(uint256 value) internal pure returns (uint256) {\r\n uint256 result = 0;\r\n unchecked {\r\n if (value >> 128 > 0) {\r\n value >>= 128;\r\n result += 16;\r\n }\r\n if (value >> 64 > 0) {\r\n value >>= 64;\r\n result += 8;\r\n }\r\n if (value >> 32 > 0) {\r\n value >>= 32;\r\n result += 4;\r\n }\r\n if (value >> 16 > 0) {\r\n value >>= 16;\r\n result += 2;\r\n }\r\n if (value >> 8 > 0) {\r\n result += 1;\r\n }\r\n }\r\n return result;\r\n }\r\n\r\n /**\r\n * @dev Return the log in base 10, following the selected rounding direction, of a positive value.\r\n * Returns 0 if given 0.\r\n */\r\n function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {\r\n unchecked {\r\n uint256 result = log256(value);\r\n return result + (rounding == Rounding.Up && 1 << (result * 8) < value ? 1 : 0);\r\n }\r\n }\r\n}"
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